博士(工学)

In China, there are about 800,000 congenital diseases among 20 million newborns, of which nearly 200,000 fetuses have serious defects or diseases. The birth of these sick fetuses brings serious economic burden and social problems to the family and even the society. It is therefore important to carry out early fetal monitoring in order to detect fetal defects and diseases as early as possible. Umbilical artery blood signals contain important information about fetal growth and development, reflecting various problems during pregnancy, such as intrauterine g rowth r etardationetardation（IUGR）, hypoxia and maternal hypertension, which can be determined by umbilical artery blood signals. Therefore, the analysis of umbilical artery blood signals is important for prenatal monitoring and fetal health status diagnosis. The acoustics pectral parameter method is a conventional technique for analyzing the umbilical artery blood signals and consists of three parameters that serve as clinical diagnostic criteria: resistance index (RI), pulsesatility index (PI) and maximum systolic/end diastolic umbilical flow velocity (S/D). However, these parameters ignore phase properties of the signal, such as phase delay, phase frequency and phase mode, and focus only on the fundamental statistical parameters of blood velocity, s uch as maximum, minimum and mean values. This may lead to clinical misdiagnosis. Umbilical artery blood signals have complicated structures and nonlinear characteristics in addition to changes in signal amplitude. This paper presents a comprehensive new approach for characteristics parameter extraction and classification of umbilical artery blood signals using fractal theory and Chaos theory in order to handle these complex structures and nonlinear properties of the signal. First, by focusing on the fract al characteristics of umbilical artery blood signals, the fractal dimension (BD) and the correlation dimension (CD) are obtained to verified that BD is positively correlated with the gestational week and CD is effective in discriminating normal from abnormal. Next, we obtain the maximum Lyapunov exponent (MLE) of the chaotic characteristics of umbilical artery blood time series, and verified its effectiveness in distinguishing normal signals from abnormal signals. Finally, a diagnostic model is proposed b y applying particle swarm optimization support vector machine (PSO SVM) to the conventional feature parameters (RI, PI, S/D) and newly obtained parameters (BD, CD, MLE) to classify and diagnose the umbilical blood signals in the four statuses (normal, oligohydramnios, umbilical cord around neck, fetal malposition). This doctoral dissertation consists of 6 chapters. Chapter 1 introduces the background and means of umbilical artery blood study as well as reviewing the current re search situation. The outline o f this dissertation is also given. In chapter 2, the fundamentals of fetal hemodynamics are described. The clinical significance and normal reference values of umbilical artery blood signal parameters are outlined. Details of the umbilical artery signal acquisition equipment, data classification and acquisition process are explained. In chapter 3，the fractal dimension box counting method (BD) and the correlation dimension (CD) are used to investigate the nonlinear characteristics of the umbilical artery blood signals based on fractal theory. First, the BD of the umbilical artery blood signals is calculated and the fractal characteristics of the signals are analyzed. Results show a positive relationship between the fractal dimension of umbilical artery blood signals and gestational weeks. A bnormal and normal umbilical artery signals are then classified into abnormal group and n ormal group. T h e Grassberg P rocaccia algorithm (GP algorithm) is used to calculate and analyze the CD of the two groups. T he overall CD of normal umbilical artery blood signals is greater than that of abnormal signal s. CD is significantly better at discriminating the normality of the umbilical artery blood signal compared to conventional parameters. Furthermore, t he Hurst exponent of umbilical artery blood signal is calculated and analyzed by Lo method. The results show that umbilical artery blood signal belong s to non sta tionary signal and show obvious “1/f fluctuation” characteristics. In chapter 4，c haotic phase space diagram method and m aximum L yapunov e xponent (MLE) are used to determine the chaotic characteristics of umbilical artery blood signals from qualitative and quantitative perspectives. The attractor reconstruction of umbilica l artery blood signals is performed in t hree d imension (3D) and t wo d imension (2D) phase space. The results show that the chaotic phase diagram of the time series for abnormal umbilical artery signals show a jumbled “ball of wool” state and the chaotic “shape” appears to converge. Application of the r eceiver o perating c haracteristic (ROC) curve to the obtained maximum Lyapunov exponent (MLE) shows that the rate of discrimination of normality of the umbilical artery blood signal is significantly better than the conventional feature parameters. In chapter 5，an artificial intelligent classifier is proposed to classify the four states of umbilical artery blood signals (normal, oligohydramnios, umbilical cord around neck and fetal malposition). The support vector machine (SVM) classifying method is constructed based on the conventional parameters, S/D, PI and RI. The particle swarm optimisation support vector machine (PSO SVM) classifier is also constructed using the fractal dimension (BD), correlation dimension ( CD) and maximum L yapunov exponent (MLE) derived in Chapters 3 and 4 as feature parameters. The results of the classification tests show that the PSO SVM classifier is more accurate , confirming the usefulness and effectiveness of the proposed classification method. In Chapter 6, summary of this dissertation and future work are described.

As the population ages, the demand for elderly care services will continue to increase, which includes providing specialized care, daily life support, and medical health services. As a result, informal caregiving provided by non-professionals such as family, friends, neighbors, and volunteers is becoming more prevalent. Injuries that occur during caregiving can affect the caregiving’s life, especially their mental and physical health. Therefore, the correct positioning and posture during caregiving are crucial to prevent musculoskeletal disorders among caregivers. Although training programs are useful to reduce the risk of musculoskeletal disorders for informal caregivers, many of them express that it is still difficult for them to grasp the correct caregiving postures. Moreover, they struggle to obtain professional advice to correct their posture through long-term practice. Therefore, finding a targeted ergonomic posture risk assessment and guidance method is crucial to improve caregivers' posture-related risks, enhance work efficiency, and safeguard their physical health. Rapid Entire Body Assessment (REBA) is a postural risk assessment method based on ergonomics that has been attracting attention recently, and it basically evaluates the risk from the angle of each joint of the body. However, in caregiving movements, the way of load placed on the caregiver and the time to maintain the movements vary greatly depending on the weight and posture of the cared person, so the current risk assessment using REBA is insufficient for caregiving movements. Additionally, posture recognition algorithms such as OpenPose are often used to extract skeletons. With these techniques, problems such as missing skeletons or misrecognition often occur due to image conditions or the overlapping of multiple people, and skeleton extraction may sometimes fail. In this research, the Spatial Temporal Graph Convolution Network (ST-GCN) is applied to develop a technique for complementing missing skeletons based on behavioral features and a technique for correcting skeletons that are misrecognized due to overlapping people, and to improve the accuracy of calculating skeletal joint angles. In order to evaluate caregiving posture risk more appropriately, some parameters such as center of gravity trajectory, load duration, asymmetric load during caregiving movements are investigated and a new REBA method is proposed. This paper consists of six chapters. In Chapter 2, to solve the problems of skeleton misidentification and missing information by OpenPose an improved skeleton reconstruction method based on ST-GCN is propose. The method compensates for missing skeletons in terms of behavioral features and corrects incorrectly identified skeletons based on skeleton weight features. This approach improves the accuracy and robustness of pose recognition and allows more accurate estimation of skeletal joint angles and its REBA score. In Chapter 3, to address the issue of REBA evaluation scores being too high for caregiving scenarios, a postural risk assessment method (C-REBA) is proposed by considering the characteristics of caregiving task. Customize the traditional REBA method and add parameters such as center of gravity trajectory, load duration, and asymmetric loading to the evaluation score. the caregiving movements to assist in transferring from a bed to a wheelchair on a group of experienced nurses and a group of inexperienced caregivers are analyzed and the effectiveness of the C-REBA method is verified. In Chapter 4, a method that combines the ST-GCN framework and C-REBA for postural risk assessment is proposed. The deep neural network algorism is applied to learn motion features and additional features such as load duration, motion frequency, center of gravity variation, and asymmetric load. So that all evaluation parameters for C-REBA rules can be obtained automatically. With this method, postural risk assessment processes in caregiving operations can be performed automatically. In Chapter 5, "Behavior Analysis and Posture Assessment System" (BAPAS) is developed. BAPAS is a system aimed at assessing the risk of musculoskeletal disorders related to working postures in medical support work. This chapter introduces the functions and usefulness of this system and demonstrates how this system can be extended to other medical fields easily by setting parameter is settings. Chapter 6 provides a summary of the paper as a whole and future prospect.

Steel truss bridges, which are one of the bridge structures applicable to long spans, are widely used as marine bridges connecting mainland and remote island. Since such steel truss bridges are built on the sea, they are exposed to severe corrosive environment due to the influence of airborne salt. In addition, there are many parts where it is not easy to inspect to detect abnormalities, so it is more difficult to eliminate the risk of member damage in such steel truss bridges than in general bridges. On the other hand, once the marine bridges are built, they become an indispensable facility for the life of the island. Therefore, if there are no other traffic routes to access an island, the sustainability of the marine bridge is an important issue that is directly linked to the sustainability of the remote island life. When member damage occurs in a steel truss bridge, it depends on redundancy, which means the margin for the load-bearing capacity and load-bearing function, whether the damage develops into chain damage or remains limited damage. Bridges with redundancy could be restored by repairing even if the member damages occurred, because they did not develop into chain damages. In some cases, vehicles could pass through with traffic restrictions. Although redundancy is an important performance for maintaining life on remote islands that have no alternative traffic routes, there are few studies on evaluation and improvement methods of redundancy for long steel truss bridges used for marine bridges. The purpose of this study is to propose a method for improving the redundancy of long steel truss bridges, and three research subjects are set to achieve this purpose. The first study subject is the investigation of the effect of truss joint modeling on redundancy evaluation, and is the subject to appropriately evaluate the redundancy of steel truss bridges. The second is also the subject related to the redundancy evaluation of steel truss bridges, and is the development of dynamic response calculation method that considers the vibration characteristics of steel truss bridges, which are vibration systems with multiple degrees of freedom. The third study subject is a proposal for methods to improve the redundancy of long steel truss bridges. This paper consists of five chapters. Chapter 1 is an introduction, and describes the background of the research, the setting of the purpose and research subjects, and the previous studies. Chapter 2 describes the study on the modeling of the truss joint. In the analysis of healthy steel truss bridges with no member damage, the sectional forces can be calculated appropriately even with analysis modeling in which frame elements of truss members are rigidly connected at the truss joints, simply. On the other hand, in the redundancy analysis of steel truss bridges with member damages, it is shown that it is necessary to consider the shape of the gusset plates at the truss joints in analysis modeling. Chapter 3 describes the study on the calculation method of dynamic response caused by damage of truss members. There are cases where the dynamic response due to member damage is calculated in the same way as a single-degree-of-freedom vibration system. However, this study develops a dynamic response calculation method considering the vibration characteristics of long steel truss bridges by using the eigenvector of steel truss bridges with member damage. A method is proposed to set the magnitude of the eigenvector using balance equation of the work given to the steel truss bridge by the sectional force unloaded from damaged member and the strain energy stored in the steel truss bridge. In addition, a method is proposed to calculate the dynamic response by setting the range of vibration modes using the sum of effective mass ratio, and selecting the eigenvector that has the greatest effect on the dynamic response for each member. It is shown that the proposed calculation method gives redundancy evaluation closer to time-history-response analysis than the method that calculates the dynamic response in the same way as a single-degree-offreedom vibration system. Chapter 4 describes the study on redundancy improvement for a long steel truss bridge. A combination of the countermeasure against members that trigger chain damage and the countermeasure against members with insufficient load-bearing capacity is planned. Analysis clarifies that the X bracing, which is a reinforcing structure in X shape, is an efficient reinforcement that works against multiple member damage cases as the countermeasure against the trigger member of member chain damage. Also, the load-bearing capacity is verified by a loading test of specimens with reinforced structures. Since the subject bridge has 18 truss panels where X bracing can be installed, the placement patterns were examined by the optimization method. It is clarified that the weight of reinforcing material can be reduced by installing X-braces only at four truss panels in the alternating areas, rather than installing at all 18 truss panels. Chapter 5 describes the summary of this study and future developments.

Since social infrastructure, which was intensively developed during the high economic growth period,will deteriorate all at once in the future, maintenance and management of facilities will be an issue in thefuture. Currently, facility inspection records are based on paperbased forms, and are not premised onautomatic processing by computer. The authors have developed the “Smart Chosa” and realized a databaseof facility inspections and a GIS System. The Smart Chosa was able to record the location of the inspectionphoto on a two dimensional map, but because it was necessary to approach the deformed part when takingthe inspection photo, it was not possible to grasp the position, direction, and size of the entire facility.Therefore, we applied 3D GIS to Smart Chosa for sabo dams, created a 3D model from photographs takenon site, and conducted research to manage inspection results on the 3D model. This study summarizes the results of research on management of inspection photographs on a 3D GISin order to improve the efficiency of management of inspection photographs of sabo facilities. This thesisconsists of 6 chapters, and the main content of each chapter is as follow. [Chapter 1: Introduction] In this chapter, the current status and issues of the maintenance and management of socialinfrastructure in Japan were summarized. Utilization of 3D models for maintenance and management ofcivil engineering facilities, high-precision positioning used for alignment of 3D models, efficientinspection of concrete structures, and existing research trends on iPhone LiDAR applications wereorganized. On that basis, the purpose and points of focus of this research were organized, and the structureand outline of this paper were described. [Chapter 2: Comparison of 3D models and examination of application to sabo facilities maintenance management system] In this chapter, three types of models, a BIM/CIM model, a 3D point cloud model, and a 3D surfacemodel, are compared and examined as 3D models to be applied to the maintenance management system.The problem setting in this chapter is the selection of a 3D model to be used in this system. The constraintis that the Sabo dams including the existing dam can be modeled in 3D. At present, there are few BIM/CIMmodels for sabo dams, so when applying to existing sabo dams, we believe that a 3D surface model thatcan be created by SfM/MVS technology from photographs taken by UAVs will be useful. The 3D modelin the research was a 3D surface model. Knowledge about the 3D model that can be applied to the sabo facility maintenance managementsystem and knowledge for utilizing the 3D model in the 3D GIS were obtained. [Chapter 3: Performance evaluation of RTK receiver used for Sabo facility investigation support system] In this chapter, a survey of high-precision positioning technology necessary for positioning 3D modelsof sabo dams and inspection photos on a 3D GIS, and evaluation of positioning performance in sabo damsand surrounding forests are conducted. The problem setting in this chapter is whether or not locationinformation can be acquired during surveys of Sabo facilities, and accuracy verification. The constraintis that real-time high-precision positioning is required using inexpensive and small devices inenvironments that are unfavorable for satellite positioning (such as sabo dams and forests). It was confirmed that the multi-band receiver whose performance was evaluated has a horizontalvariation of 22 mm (2DRMS) even in a poor environment where about 70% of the sky directly below thesabo dam is covered. It was confirmed that the method can be applied to aligning 3D models ofphotographs. [Chapter 4: Investigation of image synthesis for creation of sabo dams inspection image] In this chapter, as a basic examination of 3D model creation, the image synthesis method is organized.The problem setting in this chapter is normalization and image combination necessary for synthesizinginspection photographs (2D). The constraint is that the inspection photography equipment is a smartphonefor field survey. In the feature point detection method for image synthesis, we compared two types offeature amounts, SIFT feature amount and AKAZE feature amount, and confirmed the accuracy byexperiments. In addition, RANSAC was used as an outlier removal method. By combining these methods,we performed image synthesis using multiple photographs of the concrete surface of the sabo dam. [Chapter 5: 3D model creation by SfM/MVS and application to 3D GIS] The problem setting in this chapter is a superimposed display of a 3D Sabo dam model and inspectionphotographs. The constraint is that the equipment that can be used to create a 3D model of inspectionphotographs is limited to equipment (compact and lightweight) that can be brought by local workers. Inthis chapter, we first present an overview of the "smart chosa" system that expands the scope of applicationfrom 2D to 3D in this research. After that, we investigated SfM/MVS processing to create a 3D surfacemodel. By creating a 3D model of the sabo dam and a 3D model of inspection photos by SfM/MVSprocessing, and importing them into a 3D GIS, we succeeded in superimposing the sabo dam andinspection photos on a 3D map. In addition, we examined a method of creating a 3D surface model using the iPhone LiDARapplication that can perform 3D measurement using the LiDAR function installed from iPhone12Pro. Wecompared the 3D model created with the iPhone LiDAR app and the 3D model created using MetaShape,a software that implements SfM/MVS processing, and confirmed the image resolution and positionalaccuracy for use as inspection photographs. In order to incorporate the created 3D model into 3D GISsoftware, we examined a method for matching the orientation and position, and actually superimposedthe 3D model of the sabo dam and the 3D model of the inspection photograph on the 3D GIS. I haveconfirmed that it is possible. [Chapter 6: Summary] In this chapter, a summary of the results obtained in Chapters 2 to 5 and future issues were discussed. The result of this research is a visualization method that makes it easy for people other than fieldinvestigators to understand the situation of the site by importing 3D surface models acquired by variousmethods into 3D GIS. 3D surface models include SfM models created from photos taken with aUAV/smartphone, SfM models created from photos taken with a handheld RTK rover, and 3D modelscreated with the iPhone LiDAR app. By using this method, it is possible to grasp the deformation position and deformation direction of thesabo dam in 3D space, and by superimposing the photographs of each inspection, it is possible to graspthe change over time.

Japan's declining birthrate and aging population are difficult to resolve in the short term, and the working-age population, which refers to the population aged 15 to 65, continues to decline. On the other hand, mental illness patients are increasing in the working age population. The medical side, which is responsible for treatment, is required to improve efficiency by reforming the way doctors work. Therefore, expectations are placed on psychotherapy performed at home for the purpose of effective treatment of the working-age population. In this study, neurofeedback, which is one of the psychological therapies, was taken up, and applied equipment development and verification were carried out for its implementation at home. In this study, as a preclinical stage, measures were verified based on measurements of general cooperators. Neurofeedback (NFB) is considered to be one of psychotherapy using electroencephalogram signals, and is a psychotherapy that visualizes one's own electroencephalogram and self-controls the visualized electroencephalogram. It is attracting attention because it is a non-drug therapy and provides neuromodulation. NFB is being investigated for many clinical applications. The target diseases are diverse, including chronic pain, ADHD, depression, and mood disorders. However, we believe that there are four tasks to ensure the effectiveness of this therapy. Task 1 is overcoming the difficulty of installing electroencephalogram electrodes. NFB is considered to be a therapy that affects the plasticity of the cranial nerves, and is a therapy that actively promotes the development of neural networks, and is expected to be highly effective if the training frequency is high. It is necessary to be able to perform it at home, and it is required that electroencephalogram electrodes can be easily installed. Therefore, we made a prototype of an electroencephalogram headset with bipolar gel electrodes, and as a result of trial verification with children, we were able to confirm the electroencephalogram signals of 30 people aged 5 to 20 years old. Analysis of the recorded electroencephalogram revealed an age-dependent left-brain tendency in β waves, etc., confirming consistency with previous findings. Task 2 is determining the brain wave derivation part of the NFB training target. For electroencephalography, lead electrodes are usually placed in the scalp, but it is difficult to place the electrodes in the scalp by yourself. There is a need to consider forehead derivation for easy EEG electrode placement at home. There are regional differences in EEG waveforms within the forehead, and it is necessary to select the most appropriate extraction site. For NFB, we explored the optimal site based on the correlation with the top of the head, which is usually the electroencephalogram derivation position. Next, we performed an EEG network analysis at the time of NFB using the EEG derived from the top of the head and the EEG derived from the optimal forehead region, and analyzed the difference in the brain network during NFB due to the difference in the derivation region. For the second task, we explored the optimal site for deriving brain waves from the forehead, and proved that NFB from the brain waves derived from this site works on the same network as NFB from the brain waves derived from the top of the head. Task 3 is a method of selecting an electroencephalogram frequency band to be derived and self-controlled in NFB therapy (training target electroencephalogram frequency band). In previous studies, the EEG frequencies targeted for NFB therapy are diverse and not standardized. Even for the same disease, various electroencephalogram frequency bands are selected and NFB is performed. A personalized frequency band decision is made according to the patient's pathology and condition. In order to make the frequency band determination method more logical, we thought it necessary to determine the electroencephalogram frequency for therapy from the comparison of the basic rhythms of healthy subjects and patients. In this study, we created an electroencephalogram basic rhythm evaluation program and collected electroencephalogram basic rhythm data from randomly selected subjects. The electroencephalogram basic rhythm evaluation program consists of 7 stages. Eyes open stage, Eyes closed stage, 0Back stage, Rest1 stage, 2Back stage, Rest2 stage, Healing Picture stage. Changes in brain waves occur due to external stimuli such as eye opening and eye closing, concentration, and relaxation. An electroencephalogram basic rhythm evaluation program was created considering multiple stimuli that affect electroencephalogram dynamics. The usefulness of this program was confirmed as a preliminary examination of the dominant fluctuation region and network analysis by topographic analysis during the execution of the electroencephalogram basic rhythm evaluation program. EEG basic rhythm brain standard program electroencephalogram measurements were carried out for 89 subjects recruited from the general public, and a database was created. Using the forehead optimally measured parts (left and right) obtained in Task 2 as electroencephalogram derivation parts, a significant difference test was performed for each electroencephalogram frequency band Power value and content rate of each stage of the electroencephalogram basic rhythm evaluation program. The α Power value increased 2.52 times when the eyes were closed, and the θ Power value increased 1.67 times during 2 Back compared to 0 Back. We examined the possibility of clinical application by analyzing the correlation between the score of the questionnaire used in clinical diagnosis and the electroencephalogram component. The questionnaires used were mainly CSI (CENTRAL SENSITIZATION INVENTORY), and POMS2 (Profile of Mood States 2). Task 4 is NFB scoring. Continuation of psychotherapy requires a score as a reward to be visualized. We compared the two scores, the time ratio score and the amplitude ratio score, analyzed the correlation between the questionnaire used in task 3 and the two scores, and examined the optimal score. In results, the frequency band that correlates better with psychological activity during NFB was suggested SMR. Some of the psychological scales included the data probably above the general average level, which might have provided hypotheses at the preclinical stage. 4 tasks were conducted to demonstrate the technical requirements and effectiveness evaluation for the practical application of cognitive psychological training NFB, which is expected to be used with high frequency at home for children to working-age adults. The technological requirements and effectiveness evaluation for the practical application of NFB are presented. This research attempted four tasks and realized the possibility of frequent NFB training at home for patients from children to productive age. As a preclinical stage, it was a study within a range that can be resolved as a stage of policy verification based on the general participant study. In the future, the efficacy of this study will be further evaluated by comparing it with clinical data in the area of mental illness such as depression and developmental disorders, including chronic pain. In the future, the effectiveness of this study will be further evaluated by comparison with clinical data in the area of chronic pain and other mental illnesses such as depression and developmental disorders.

Open source software (OSS) are adopted as embedded systems, server usage, and so on because of quick delivery, cost reduction, and standardization of systems. Therefore, OSS is often used not only for the personal use but also for the commercial use. Many OSS have been developed under the peculiar development style known as the bazaar method. According to this method, many faults are detected and fixed by developers around the world, and the fixed result will be reflected in the next release. Also, many OSS are developed and managed by using the fault big data recorded on the bug tracking systems. Then, many OSS are developed and maintained by several developers with many OSS users. According to the results of the 2022 Open Source Security and Risk Analysis (OSSRA), OSS is an essential part of proprietary software, e.g., the source code containing OSS is 97%, all source code using OSS is 78%. On the other hand, OSS has issues from various perspectives. Therefore, OSS users need to decide on whether they should use OSS with consideration of each issue. In addition, the managers of open source projects need to manage their projects appropriately because OSS has a large impact on software around the world. This thesis focuses on the following three issues among many ones. We examine a method for OSS users and open source project managers to evaluate the stability of open source projects. 1. Selection evaluation and licensing: Methods for OSS users to make selections from the many OSS available situation, 2. Vulnerability support: Predicted fault fix priority for the reported OSS, 3. Maintenance and quality assurance: Prediction of appropriate OSS version upgrade timing, considering the development effort required after OSS upgrade by OSS users. In “1. Selection evaluation and licensing,” we attempt to derive the OSS-oriented EVM by applying the earned value management (EVM) to several open source projects. The EVM is one of the project management methodologies for measuring the project performance and progress. In order to derive the OSS-oriented EVM, we apply the stochastic models based on software reliability growth model (SRGM) considering the uncertainty for the development environment in open source projects. We also improve the method of deriving effort in open source projects. In case of applying the existing method of deriving effort in open source projects, it is not possible to derive some indices in the OSS-oriented EVM. Thus, we resolve this issue. The derived OSSoriented EVM helps OSS users and open source project managers to evaluate the stability of their current projects. It is an important to use the decision-making tool regarding their decisions and projects of OSS. From a different perspective, we also evaluate the stability of the project in terms of the speed of fault fixing by predicting the time transition of fixing the OSS faults reported in the future. 2. In “Vulnerability support”, in terms of open source project managers, we create metrics to detect faults with a high fix priority and predicted a long time for fixing. In addition, we try to improve the detection accuracy of the proposed metrics by learning not only the specific version but also the bug report data of the past version by using the random forest considering the characteristic similarities of bugs fix among different versions. This allows the project managers to identify the faults that should be prioritized for fixing when a large number of faults are reported, and facilitates project operations. In “3. Maintenance and quality assurance”, as an optimum maintenance problem, we predict the appropriate OSS version-up timing considering the maintenance effort required by OSS users after upgrading the OSS. It is dangerous in terms of the vulnerability to continue using the specified version of OSS ignoring the End of Life. Therefore, we should upgrade the version periodically. However, the maintenance cost increase with the version upgrade frequently. Then, we find the optimum maintenance time by minimizing the total expected software maintenance effort in terms of OSS users. In particular, we attempt to reflect the progress of open source projects by using the OSS-oriented EVM in deriving the optimal maintenance time. In conclusion, we found that there is the applicability as the stability evaluation of open source projects from three perspectives. Particularly, the OSS-oriented EVM discussed in “1. Selection evaluation and licensing” can contribute to the visualization of maintenance effort in open source projects. The proposed method will potentially contribute to the development of OSS in the future.

Indonesia has extreme risk of natural disasters because of its position at the confluence of four tectonic plates: the Asian Continent, the Australian Continent, the Indian Ocean, and the Pacific Ocean. The volcano eruption is one of the geological disasters that frequently occur in this country. Mount Merapi is Indonesia’s most active volcano and is famous worldwide. The evacuation crisis in 2010, the last major eruption, led to many fatalities for humans and cattle. Nowadays, the local government developed the "sister village" strategy for mitigation. That means cooperation within or between the local community has been constructed to provide shelter, logistics, and other disaster-related services. In this scenario, the meeting area and shelter have been coordinated. However, people's behavior has not been fully considered yet in the vulnerability assessment and government's contingency plan. On the other hand, evacuation issues in a volcanic disaster such as difficulty in expecting evacuation period, aging population, missed communication and risk perception, limited private vehicles in the community, and limited evacuation transport and supporters by the government need to be addressed for better mitigation. This situation led some people to walk to the meeting area, and low walking speeds by vulnerable persons may increase the risk and delay during an emergency. The objective of this study is to find the effectiveness of the evacuation process, especially for the vulnerable community in the Mount Merapi area. Especially, this study purposes to develop a “mutual assistance” model for vulnerable people in the affected regencies with the people’s behavior and vehicle ownership as a viewpoint. The first goal is an assessment of the mutual assistance strategy and social vulnerability index (SoVI) of pedestrian evacuation. I conducted the surveys and then analyzed the data using a multicriteria method to obtain the SoVI values for communities. The second goal is the development of the assembly model to support safer and faster evacuation for vulnerable people. The AnyLogic software was selected for model simulation using input parameters from field surveys. In conducting a survey, I measured the walking speed directly of the evacuation drills in four affected regencies. I also investigated the people’s behavior and eruption characteristics using an interview process with stakeholders and group discussions with local communities. After that, I used the multicriteria method and focused on two factors, social and age structure (young, vulnerable, and mutual assistance between them), and risk perception (work, rain, night, alert, and evacuation map). The index reflects the distribution of actual walking speed, mutual assistance, and the government's plan. The result showed that mutual assistance groups have a higher walking speed than vulnerable people but lower than young people. Mutual assistance coordination is crucial to support the vulnerable in shorter evacuation times. The social and age structure of the social vulnerability index has a stronger risk influence than the perception factor in the evacuation process. The successful evacuation of vulnerable people during emergencies is a significant challenge. In this study, a mutual assistance strategy is proposed to support vulnerable people by evacuating them with young people. This strategy was simulated using AnyLogic software with the agent-based model concept. Pedestrians and vehicles played the roles of significant agents in this experiment. Evacuation departure rate, actual walking speed, group size, route, and coordination were crucial agent parameters. Residents’ attitudes, distribution of each agent, and actual walking speed were obtained from surveys. Then, I developed three scenarios and three models for the evacuation process. Scenarios considered traffic conditions of evacuation routes and models represented behavior approach. The results revealed that this mutual assistance model is effective for the rapid evacuation and risk reduction of vulnerable communities where successful evacuation rates have improved. As for mutual assistance behavior, Model 3, where young people are matched with vulnerable people in advance, has shown better results than Model 2. Additionally, Scenario C, where pedestrians have separate lanes from vehicles during the evacuation process, has resulted in more number of vulnerable people reaching the shelter than Scenario B in Model 3. The highest arrival rate was obtained by the combination of scenario C and Model 3. These findings are a novelty in the volcano context and reflect all categories of vulnerable behavior involving the elderly, disabled, children, and pregnant mothers. The model will benefit disaster management studies and authorities’ policies for sustainable evacuation planning and aging population mitigation.

Access to clean water has been crucial global problem, especially with climate change, increasing population, and industrial activities. As one of Malaysia’s leading economic activities, the Oil and Gas Industry generates a massive amount of wastewater called Produced Water (PW). Dissolved organics in produced water, such as organic acids and phenolic compounds, are concerning due to the possibility that they can be toxic, non-biodegradable, and have bioaccumulation properties. Conventional treatments such as adsorption, incineration, and biological treatment seem to have difficulties treating these dilute but toxic components in an economical and environmentally friendly manner. Regulations on wastewater management has also been stricter around the globe. Therefore, there is a need on a new water treatment method to treat the diluted organics in a large volume of wastewater. Membrane technology has been of interest in the water treatment technologies’ industrial and research scenes. It offers simpler configuration and maintenance. However, the application is limited by the reduction of performance over time due to fouling phenomena. Photocatalyst offer an effective method to decompose organics in an environmentally friendly manner. This study researched on photocatalytic removal of diluted organic in water and potential of biofouling reduction by deposition of AgTiO2 coating on membrane surface. In Chapter 1: Introduction, the research background and purpose of this research were discussed. At the end of this chapter, the thesis framework was shown. In Chapter 2: Preparation and characterization of TiO2 and AgTiO2 coatings; the method to prepare AgTiO2 coatings on membrane support were explained. The prepared membranes were characterized with XPS, SEM, TEM, and ICP analysis to understand the prepared coatings. Results shows that the concentration of silver deposited on the membrane can be control by the concentration of silver in the precursor (silver acetate solution) used during the photochemical deposition step. Via XPS, it was found that the state of silver prepared through this method is oxide state. In Chapter 3: Removal of dissolved organic pollutants in water by photooxidation, the photocatalytic performance of prepared membranes was studied. Decomposition of diluted formic acid was performed under UV-light, and the concentration was evaluated using UVspectrophotometer. AgTiO2 membranes show better photocatalytic activity then TiO2 membrane. The concentration of silver on the membrane was found to influence its photocatalytic performance. In relation to PW application which commonly contain high salts, influence of salt types; NaCl, MgSO4, MgCl2 and K2SO4 and concentration were studied. All salts were found to inhibit the membranes’ photocatalytic performance. In Chapter 4: Antibacterial activity of AgTiO2 membranes, the antibacterial activity towards E. coli by prepared AgTiO2 membranes were investigated. Silver dissolution from membrane was found to be significantly increased in the presence of NaCl as compared to only water. Comparing membrane with lower Ag deposition, and around 20 times higher deposition, the silver dissolution from these membranes reached almost the same value after some time. However, as the amount of silver deposited on the membrane was higher, the antibacterial performance show around four times higher than the lower silver membrane. Based on other tests performed, it was concluded that there are potential of contribution from the silver oxide deposited on the membrane surface on the antibacterial activity of the AgTiO2 membranes In Chapter 5: Antibacterial activity in filtration system, prepared AgTiO2 membrane was used to filter E. coli suspension in water. E. coli growth was found to be inhibited by short contact with silver on the coated membrane. Finally, Chapter 6: Conclusion, the thesis was summarized, and future works were proposed.

In recent years, many reports have been made of damage to reservoir embankments due to frequent heavy rains and earthquakes. “Internal erosion” is the phenomenon in which soil particles move through the pore spaces of embankments and flow out of them because of long-term seepage in the soil structures of reservoirs and river embankments. Internal erosion is classified according to the scale and form of the erosion. “Suffusion” is the phenomenon in which only the fine-grained soil particles move through the pore spaces formed by the coarse-grained soil particles. Suffusion is known to cause an increase in hydraulic conductivity and a decrease in soil bearing capacity. However, the mechanisms and causes of the occurrence and progression of this phenomenon, as well as its effect on soil structures, have not been fully elucidated. Therefore, the purpose of this study was to clarify the effect of suffusion on the strength properties of reservoir embankments as well as the mechanism of the progression of suffusion, focusing on the particle size of the eroded soil particles. In Chapter 1, the background of the study and the classification of internal erosion were provided. In Chapter 2, the mechanism of suffusion and its effect on geomaterials, which have been clarified in previous studies, were described. In Chapter 3, the effect of suffusion on the strength properties was firstly investigated by means of soil samples used for the reservoir embankments which were determined to be at risk of suffusion based on an internal stability evaluation. A triaxial compression testing system was established to simulate the suffusion inside each specimen. In the testing system’s apparatus, only the fine particles were able to be discharged from the specimen through a sieve by supplying water. The results showed that changes in the peak and residual strength occurred independent of changes in the void ratio due to suffusion, and that the strength properties differed depending on the presence or absence of suffusion, even when the void ratio was the same as that before shearing. However, since the amount of erosion was small (less than 0.7% of the total), it is considered that the change in strength was influenced by the fine soil particles that moved through the specimen but remained in the specimen without finally flowing out of it. In Chapter 4, in order to define the mechanism of small-scale internal erosion, a method was devised to examine the temporal changes in the size of the discharged soil particles, focusing on the relationship between the concentration and the turbidity of the drainage. The above method was also applied to the drainage obtained by seepage with suffusion in Chapter 3. As a result, the erosion rates were found to correlate with the particle size of the discharged particles. In Chapter 5, a one-dimensional water-passing experiment with suffusion was conducted to investigate in detail the relationship among the flow rate, soil particle discharge, and turbidity of the drainage. The particle size composition of the discharged soil, which varied with the progress of suffusion, was examined using the method described in Chapter 4. The results showed that, under all conditions, the soil particles with smaller diameters were selected from among those that were able to pass through the wire mesh at the outlet boundary and then discharged. It was also found that the particle size composition of the discharged soil changed with time as the suffusion progressed, and that this trend varied greatly depending on the saturation degree of each specimen before the start of permeation. After the completion of the experiment, the particle size composition of the soil samples showed that not only the distribution of the erodible component in the height direction, but also the particle size composition of the erodible component itself became heterogeneous, suggesting that soil particles with smaller particle sizes moved longer distances through the pores. Furthermore, the effect of overburden pressure on the behavior of suffusion under constant hydraulic gradient conditions was explored, and it was revealed that higher overburden pressure resulted in less frequent suffusion when the hydraulic gradient was large. The particle size composition of the discharged soil was examined, and no difference was found among the various levels of overburden pressure. In addition, the progression of suffusion was investigated under a fluctuating hydraulic gradient. The suffusion continued even after 30 cycles of hydraulic gradient variation. The particle size composition of the discharged soil particles showed that the small soil particles, that flow easily, had already been discharged when the specimen was first subjected to permeation force, and that the soil particles discharged by the change in hydraulic gradient were relatively large in diameter. The particle size of the soil particles discharged by suffusion were seen to depend on the conditions surrounding the occurrence of suffusion and the time of the progression. In studies on suffusion, the particle size composition of the soil discharged by suffusion is a significant factor that changes over time and can be used to evaluate the degree of the progression of suffusion.

Sleep is an essential physiological process for the human body. People spend about one-third of their lives sleeping. Both sleep duration and sleep quality are important to human health. Sleep quality describes how restful and restorative the sleep process is. Over 80 sleep disorders are known to affect sleep quality. Among them, sleep-related breathing disorder (SRBD) is the second factor. Sleep-related breathing disorders are sleep disorders in which breathing abnormalities occur during sleep. Abnormal snoring and respiratory arrest or abnormally low breathing during sleep reduce oxygen levels in the blood, increasing the risk of depression, cardiovascular disease, stroke and even death. Therefore, monitoring and analysis of respiration during sleep is gaining increasing importance in healthcare. Polysomnography (PSG) is considered the gold standard for diagnosing sleep disorders, but PSG is usually performed in an unfamiliar sleep laboratory under the supervision of a medical technician and is often worn with many sensors that interfere with sleep. It is often the case. This research group is developing a breathing sound measurement system that constantly monitors the quality of sleep in general home environment. This system can easily measure breath sounds during sleep all night with high accuracy without disturbing sleep. The purpose of this research is to develop a technique to classify patterns of breathing sounds and to analyze the quality of breathing in order to more accurately analyze the state of sleep from breath sound information. There are various patterns of sleep breath sounds, such as normal breath sounds and snoring, and abnormal breath sounds and snoring. To develop a method to classify these patterns, to develop an algorithm to calculate ventilation from breath sounds, to estimate the sleep apnea index (AHI), and to assess the quality of breathing during sleep. try. Specifically, the temporal feature waveform (TCW) is calculated after partly removing the noise of the breathing sounds of sleep with a band-pass filter. Based on the time feature waveform, a respiratory signal effective for analysis is extracted from low-level signals and phase-divided into a respiratory phase and an apnea or low signal. Mel-frequency cepstrum coefficients (MFCC) are then obtained for the respiratory phases, and an agglomerative hierarchical clustering (AHC) algorithm is applied to distinguish between normal/abnormal breathing, normal/abnormal snoring, and normal/abnormal breathing. , tossing and turning, etc., which are less relevant to breathing. The categorized breathing patterns are analyzed every 30 seconds and the relative tidal volume of the breath is calculated. In addition to verifying the effectiveness and accuracy of the technology and analysis method proposed in this study, a method of estimating the apnea syndrome index (AHI) and converting the ventilation volume into high, medium, and low levels, We propose a method to evaluate the quality of breathing in a patient and verify its effectiveness. This paper consists of six chapters, including an introduction and conclusion. Chapter 1 introduces the background and overview of this research. Chapter 2 describes a signal-processing technique for analyzing breath sounds during sleep and a method for classifying breathing patterns. Breathing sound data during sleep often includes disturbed breathing due to bruxism or body movement, ambient environmental noise, etc. In this chapter, the Time Characteristic Waveform (TCW) and the Characteristic Moment Waveform (CMW) are calculated for respiratory sound signals that have undergone preprocessing, such as filtering noise to preprocess the respiratory sounds, and the segmentation of inspiration and expiration is performed. The Mel-Frequency Cepstrum Coefficients (MFCC) are obtained for each respiratory cycle and applied as a feature vector to the Agglomerative Hierarchical Clustering (AHC) algorithm. This method is used to classify ordinary respiratory signals (normal and abnormal breathing, normal and abnormal snoring) from signals less relevant to respiration, such as tossing and turning and environmental noise. In Chapter 3, using the technology described in Chapter 2, breathing sound data during sleep are classified into apnea, hypopnea, normal breathing, abnormal breathing, normal snoring, and abnormal breathing for each 30-second frame. In addition, we describe a method for classifying events such as no snoring and rolling over and determining the respiratory state. In Chapter 4, we propose a method for estimating the apnea-hypopnea Apnea-Hypopnea Index (AHI) for classified abnormal breath sounds and low-level breath sound signals, compare it with the diagnostic results of PSG, and examine its validity. And verify usefulness. Chapter 5 describes a method for estimating ventilation volume from breath sounds. Because normal breath sounds are correlated with ventilation, this study used a quantitative approach to calculate normal breathing and normal snoring and a qualitative method to calculate apnea/hypopnea and abnormal breath sounds. We will propose and compare it with the diagnosis result of PSG and verify its validity. In Chapter 6, as an application development, an example of applying the breathing sound classification method proposed in this study to heart sound analysis is presented. Finally, we will explain the construction of a data collection distribution system for sharing auscultation data collected at different facilities and hospitals using blockchain technology. Chapter 7 presents the conclusions and prospects of this study.

Innovation is the practical implementation of ideas that result in the introduction of new goods or services or the improvement in them (Schumpter, 1983). Innovation is closely related to invention as innovation is more on involving the practical implementation of a new or improved invention to make a meaningful impact in a market or society (Schumpter, 1939). On the other hand, innovative design is a process of identifying, pinpointing, and understanding the needs of the user or audience (Shaulis, 2021). Previously, Dixon (1966) defined innovative design as any design that is: new or different, or elegant or uses new ideas, or is an improvement over its peers. Once the market need has been identified, a solution can then be designed. In our proposed innovative design method, we introduced and investigated a method that is able to be applied in designing an intergrated system that could be a valuable solution to the society. This method starts with directly observe activities of things and real people in real trouble in the real field. Then, we think about the value of "I wish there were such things as…", visualize the story, draw a clear sketch to accomplish the story concretely. Next, we solidify the functions and specifications while investigating needs and competition. Then, we create a prototype that able to show and test your ideas, demonstrate to the people who need it, let them experience it, and gain feedback. Lastly, we evaluate the value of product design and development and plan methods for implementing it as an organization, and plan ways to improve and expand globally. All of the steps in this method are important for innovative design, however, in this research this time we focused on co-designing value, big idea, and considering as integrated steps for identifying latent needs of the consumers. It is because identifying needs is an important part in the product development process. Latent needs are those that many consumers recognize as important in a final product but unable to articulate in advance (Ulrich, 2015). The latent needs addressed in this study was focusing on identifying consumer requirements in product development in the innovative design method. The challenge in identifying latent needs is finding the method to elicit from consumers the needs which are not addressed by any inventors yet in the present market but would delight the consumers if delivered tomorrow. The purpose of this study is to propose and verify the method in the elicitation of latent needs from consumer needs by introducing a working prototype to the consumers, interviewing, and analyzing responses from the consumers. This research was conducted during the year the start of the COVID-19 pandemic. As the pandemic spread, most countries were forced to go into lockdown or declare an emergency state. The school was closed and business organizations needed to switch to working from home to prevent the spread. The parents were unable to work from home efficiently as they were worried their children will involve in dangerous incidents if the children were left by themselves. Based on this situation, this study was conducted in finding the latent needs of the parents, childcare workers, and children in order to assist them in going through their problems during this COVID-19 pandemic. The working prototype was used as material to prepare presentation slides for the consumers' interviews. The first presentation slides were focused on the background problems and ideas for the solutions while the second presentation slides provided consumers with a prototype and story of the product that was believed would be one of the solutions to the problems. Interviews were conducted after both slide presentations. Consumers' responses were obtained and interpreted into consumers' needs in terms of product functions. In the first study, consumers' interpreted needs from Problem-based interviews and Prototype and Story-based interviews were compared. Based on the results, latent needs interpreted from interviewees' responses and the categories of the needs obtained from the Prototype-based interviews are more than from the Problem-based interview. The latent needs that we were able to obtain from this research were for example, “The device is able to detect small changes in a child while watching he/she sleeping” which could lead into the prevention of unwanted incident such as sudden infant death syndrome (SIDS). This supports our assumption that showing working prototype-based materials with story descriptions can be effective in uncovering potential latent needs. In the second study, it is assumed that experience, empathy, and knowledge of working prototype is essential elements in product development, therefore, new additional guidelines which are “to write a statement with empathy”, “to write a statement as a designer”, and “to write a statement as someone with experience” were proposed during consumers' needs interpretation to see whether these new guidelines will influence the process of identifying latent needs of consumers. From the result, it is concluded that the number of interpreted needs increased when we applied the new proposed guideline. Although the number is small, the needs might not be interpreted if the new guidelines were not considered. We were also able to obtain a few important latent needs when we applied these new guidelines. A latent need collected from applying the guideline "to write a statement as someone with experience" is “The device is not for teaching love and humanity but for monitoring by watching facial expression, posture, and vital signals such as temperature and heart rate”. We could conclude that including these guidelines upon interpreting raw data from the consumers’ interviews might lead into discovering important and critical latent needs of the consumers. In the third study, a quantitative evaluation method for identifying latent needs was introduced. The consumers' interpreted needs were rated according to a basis of rating from the three perspectives of importance, latent-ness, and technological feasibility. The Degree of Latent Needs (DLN) was calculated by multiplying these three metrics. Based on the result for the average and variance of DLN mean value for each evaluator which is sufficiently small, it indicates that the basis of rating for three metrics of the DLN is effective. The results also indicate that the 20 highest DLN points of the interpreted needs contain attractive features in terms of design. However, we had gotten some pushback on the average of each interpreted need and its variance which indicates opposing opinions among evaluators. As it is possible that attractive needs are hidden and may lead to the discovery of latent needs through individual pinpoint interviews, the interviews with the minority evaluators were conducted. The interview results indicate that the latent needs with low DLN rates but valuable might be able to be discovered by conducting follow-up interviews such as “The device is able to recognize items (food or not) that a child wants to put in the mouth”. From the results in all three studies, we could conclude that a number of important latent needs are able to be elicited from consumers’ needs by applying the proposed method. In our fourth study, a decision-making method based on the patent analysis between the conceptual design stage and the prototyping stage in the innovative design method was introduced. Conducting a patent strategy was assumed to support how to select the right concept precisely. In this study, by conducting a patent search in this stage by the designer who understood best the product functions and working principles, a supporting method was introduced to assist the designer in their decision-making process. Based on the result, the method was able to observe whether there are dominating companies or not for our concept design. If there is a dominating company, the possibility of not being able to produce our concept becomes bigger. This method may be applied as an indicator to support decisionmaking in the concept design stage in the innovative design method, whether to proceed with the concept design or not and to reduce the possibility of product failure in the future. From the results of all the studies, we could conclude that these above methods may be applied as assistive tools to support designers’ understanding of consumers’ requirements and selecting the right concept design.

Some textbooks of formal languages and automata theory implicitly state the structural equality of the binary n-dimensional de Bruijn graph and the state diagram of minimum state deterministic finite automaton which accepts regular language (0+1)*1(0+1)^{n-1}. Although the isomorphism in binary case is relatively easy to prove, it is desirable to rigorously prove such an isomorphism in general k-ary case. To achieve this purpose, the author introduces a new computational model, called "colored finite automata (CFA)," and give a certain characterization of the general k-ary de Bruijn graphs by regular languages. The second purpose of this study is to investigate the potential of this automaton with multi-colored accepting states. By the way, when CFA is nondeterministic (NCFA), it is desirable that the colors of accepting states are unmixed (i.e., there are no inputs that are accepted with differently colored accepting states) in order to pursuit the accurate identification. Thus, the author proposes the three decision problems (Unmixedness Verification problem, Unmixedness Partitioning problem, and Unmixedness Extension problem) concerning unmixedness and show that UV, UP, and UE problems are shown to be NLOG-complete, P, and NP-complete, respectively. The author also illustrates the applications of colored finite automata, e.g. to existing regular expression engines and model checking tools for the purpose of improvement of their efficiency and conveniency. Next, the author introduces "colored pushdown automaton (CPDA)" which is an ordinary pushdown automaton with colored accepting states. It is shown that while the computational complexity of the above-mentioned UV, UP, and UE problems of CPDA are all undecidable, restriction of CPDA are all undecidable, restriction of CPDAs to unambiguous ones simplifies some problems of them to the permanently true problems. In this way, the concept of colored accepting states can be applied to a wide range of automata that have a set of accepting states and expected to be useful in a wide range of theoretical and practical field of automata applications in the future.

Rapid population growth and economic progress over the past decades have triggered a sharp increase in the global demand for fossil fuels thereby resulting in an energy crisis. The problem may be alleviated by upgrading and producing gaseous energy, but one of the major challenges associated with gaseous energy is to separate it effectively from other less desirable gases. Thus, energy-saving and high-efficiency separation technology is needed. In the past three decades, gas separation membranes, including polymeric membranes and inorganic membranes, have attracted much attention due to their advantages in terms of energy efficiency, operational simplicity, cost competitiveness, and small footprint. Although polymeric membranes have been utilized in practical gas separation, their separation performance is not sufficient for widespread practical application. Carbon molecular sieve (CMS) membranes, one of the inorganic porous membranes, can be prepared by pyrolyzing polymeric precursors.Their pore structures provide molecular sieving ability and possess good thermal and chemical resistance. Especially, the separation properties of the CMS membranes for a variety of gas pairs have exceeded the upper bound of polymeric membranes. These characteristics have made them attractive candidates for gas separation. The pore structures, separation properties, and transport mechanism of the CMS membranes depend critically on the type of the polymeric precursors, pyrolysis conditions and pre- and post-treatments. Thus, in this thesis, I prepared CMS membranes derived from different polymeric precursors and investigated the effect of pyrolysis conditions and post-treatment on the gas permeation properties. In Chapter 2, toluene vapor addition was performed for the first time during the pyrolysis process to prepare highly selective CMS membranes. Adding toluene vapor in the pyrolysis process was a simple method to improve the selectivity compared with the traditional chemical vapor deposition post-treatment technique. Additionally, the use of toluene can avoid the high transportation costs of gaseous hydrocarbons. The results indicated that toluene vapor addition increased selectivities of the H2-related gas pairs compared with CMS membranes without toluene vapor addition. This could not be realized simply by increasing the pyrolysis temperature without toluene vapor addition. The CMS membrane with toluene vapor addition also showed higher permeance with a moderate selectivity compared with the CMS membrane with gaseous hydrocarbon addition reported in the literature. Furthermore, the gas permeance and selectivity could be readily controlled by adjusting the pyrolysis temperature and duration of the addition. The optimal preparation conditions of the CMS membrane with toluene vapor addition depend on the targeted gas pair to be separated. This study indicated that adding liquid hydrocarbon vapor in the pyrolysis process can be a simple and effective method for preparing highly selective CMS membranes. In Chapter 3, the mechanism of achieving high selectivity for the CMS membranes prepared by adding toluene vapor was further investigated. The physical and chemical properties of CMS membrane with adding toluene vapor were characterized using some sophisticated characterization techniques. It was found that toluene vapor addition formed carbon deposition on the outer surface region of the CMS membrane, which agreed with the previous report. The gas adsorption experiment suggested that toluene vapor addition also resulted in the loss and the narrowing of ultramicroporosity. Additionally, I preliminary analyzed the mechanism of achieving high selectivity for the CMS membrane with toluene vapor addition. In Chapter 4, a novel porous carbon fiber (PCF) was investigated to prepare supported CMS membranes derived from wood tar solution, as the development of wood tar-derived CMS membranes has been limited by the availability of porous supports in recent years. Moreover, the CMS membranes supported on commercially available porous ceramic tubes were also prepared under the same conditions for comparison purposes. The PCF consisted of interconnected pore structures, which provide additional paths and channels for gas transport, whereas the porous structure of the ceramic support consisted of voids between the alumina particles. It was found that for both supports, 70 wt% wood tar solution was the optimal solution for preparation of CMS membranes. The PCF-supported CMS membranes exhibited higher gas permeance and selectivity than the NA3-supported membranes. Furthermore, a series of PCF-supported CMS membranes from 70 wt% wood tar solution were prepared at different pyrolysis temperatures, the membrane pyrolyzed at 600 °C exhibited the highest H2 selectivity. This study demonstrated that PCF can be used for supported CMS membranes derived from wood tar solution. Additionally, PCF is also a promising support for the supported CMS membranes derived from other polymeric precursors. Finally, Chapter 5 summarized the main contents of this thesis.

It is important to anticipate problems such as a large amount of spring water that occurs during shafts construction and maintenance problems such as concentration of lining cracks after shafts construction in advance, and to carry out construction in a rational manner. Crack tensor from the rock mass information (cracks, strength) obtained by the construction of the shafts of the Horonobe Underground Research Laboratory of the JAEA, aiming at the selection of support and the implementation of spring water countermeasures. Based on the theory, the research results were summarized with the aim of evaluating the water hydraulic conductivity of the rock mass during shafts construction and the deteriorated condition of the lining after shafts construction, and establishing a simple prediction method for these. Chapter 1 summarizes the current state of rock mass geological observation and lining maintenance in the shafts, the water permeability coefficient of the rock mass, and the past domestic and overseas studies on the deterioration state of the lining, and the hydraulic conductivity of the rock mass using the rock mass information. The purpose of this study was clarified with the task of evaluating the deterioration state of the lining and establishing these simple prediction methods. In Chapter 2, crack tensor theory and stereology (statistical geometry) are used using information (length, direction, opening width) of rock cracks during shafts construction. By applying the concept, the three-dimensional permeable tensor was estimated accurately. Then, when the hydraulic conductivity obtained from the three-dimensional hydraulic tensor and the hydraulic conductivity based on the result of the in-situ permeability test using the deep borehole near the shafts were compared, it was clarified that they were in good agreement. A high correlation was obtained between the crack frequency obtained by dividing the total length of the cracks obtained in the shafts construction by the evcavation surface area and the hydraulic conductivity obtained from the three-dimensional hydraulic tensor. Therefore, we proposed a method to easily predict the hydraulic conductivity of rock from the frequency of cracks. The obtained prediction formula targets the depth at which three cross sections orthogonal to each other can be obtained on the rock crack observation surface, but the prediction formula was also obtained at a depth where three cross sections orthogonal to each other cannot be obtained. Comparing the hydraulic conductivity of the rock mass and the hydraulic conductivity based on the in-situ permeability test results, it was clarified that they are in good agreement. In Chapter 3, the orientation dependence of the earth pressure is recognized in the underground environment of the Horonobe Underground Research Center, and it is the major principal stress direction in the shafts of the underground Laboratory. Cracks have occurred on the lining wall surface in the east-west direction. However, the lining cracks in the shafts at that point may depend not only on the orientation dependence of the ground pressure, but also on the rock cracks on the back surface of the lining, the ground cover and the rock strength. If a prediction formula for predicting lining deterioration can be created in consideration, it will be useful information for countermeasures during construction, and based on the crack tensor calculated based on the information on cracks, from the rock crack tensor and rock strength. I proposed a method to estimate the deterioration condition of the lining. The estimated value of the crack tensor regarding the deterioration of the lining using the obtained prediction formula and the measured value calculated from the information of the lining crack, assuming that the margin of error due to the relative error is 0.1, the estimated value and the measured value are well one. Im adei t clear that Ia md oing it. In Chapter 4, aiming at selection of rational support for shafts extension of underground Research Laboratory planned in the future and implementation of spring water countermeasures. Ip roposed ac onstruction management system that applies the crack tensor prediction method for rock hydraulic conductivity during shafts construction and deterioration of lining after shafts construction. In the future, in order to select more rational support and implement measures against spring water, the rock mass information (cracks and rock mass strength) acquired during shafts construction will be obtained using the prediction formulas established in Chapters 2 and 3. By predicting the hydraulic conductivity of the rock and the crack tensor related to the deterioration of the lining, and reflecting it in the measures against spring water in the rock mass and the measures against the deformation of the lining, it can be expected to contribute to the reduction of maintenance costs. Chapter 5 summarizes the research results in each chapter and raises future issues for conclusion.

This PhD thesis addressed current knowledge gaps regarding microplastic pollution as well as developed new insights into occurrences and fate of microplastics within marine and freshwater systems,prominent sources-to-sinks phenomena,and ecological risk assessments with global relevance.

Many infrastructures constructed in the period of high economic growth are currently deteriorated and need renewal / repair. Considering the future situation, new-build infrastructures should be more durable, so the use of high-strength materials capable of reducing maintenance and management costs is preferable. A suitable construction material for the future situation is an ultra-high-strength fiber-reinforced concrete (UFC). General UFCs are cured under high temperature (at 90℃ for 48 hours). Most UFC members are often made in precast-concrete factories with dedicated curing facilities. A UFC manufacturable at general ready-mixed concrete plants has been required for various constructions using cast-in-placed concrete. The study focused on the mixture design and the manufacturing method of UFC without heat-curing. The targeted strength of the UFC was 200 N/mm^2 at the concrete age of 28 days. To achieve the required performance for UFC, the experimental study was designed and conducted. The thesis consists of seven chapters, and the content of each chapter is as follows: Chapter 1 "Introduction" shows the social concern in Japan, such as the present conditions of infrastructures. In addition, the chapter summarizes the transition of high strength concrete and fiber-reinforced concrete. The research background and the purpose of this study are described in this chapter. Chapter 2 "Previous studies" shows the review of previous studies dealing with investigations on UFC. In addition, the chapter clarifies the problem of UFC manufacturing by referring to the previous studies. Chapter 3 "Mixture design", the materials and mixture proportions required for the UHPC manufacturable under ambient temperature conditions were investigated. Five types of cement and four types of powder materials were tested, as well as the fine aggregate needed to achieve proper fluidity, fiber dispersibility and strength. To achieve the appropriate flowability and adequate strength, the cement having low C_3A and high C_3S was suitable for the UHPC manufacturable at ambient temperatures. Furthermore, the mortar with W/B of 21% achieved 200 N/mm^2 at 28 days, so it can be designed as the maximum W/B for the UFC. The test result confirmed that allowable fine aggregate volume was lower than 600 kg/m^3 to obtain proper dispersion of steel fibers. Chapter 4 "Material properties and durability of hardened UFC", the hardening material properties and durability of the UFC designed in Chapter 2 were examined. The result confirmed that the UFC achieved 196 N/mm^2 at the age of 28 days. The UFC exhibited an excellent cracking strength and tensile strength which were almost equivalent strength of the conventional UFC. In addition, the UFC indicated excellent resistances to various degradation effects, such as neutralization, freezing and thawing, permeability of chloride ions, and sulfate attack. On the other hand, the UFC had low resistance to sulfuric acid and large autogenous shrinkage strain. The properties should be considered in the application of prestressed concrete owing to the loss of prestress. Chapter 5 "Manufacturing method in RMC plant" reports the manufacturing methods at the ready-mixed concrete (RMC) plant. The result confirmed that UFC can be manufactured at a general RMC plant, the equipment although mixing time varies owing to the mixer capacity. In addition, the mixing methods of steel fibers were compared. Owing to the high viscosity of the UFC, undischarged UFC from the truck was approximately 190 L, which was extremely higher than ordinary concrete (80 L). The compressive strength of UFC using several types of fine aggregate were examined. The result suggested that the evaluation of the properties of fine aggregates in the UFC is necessary for the practical use. Chapter 6 "Practical applications of UFC" verifies the applicability of UFC of at sites. The result confirmed that the mixing-load increased in proportion to the mixing volume, the maximum mixing volume was identified as 80% of the capacity of mixer. The results showed that the UFC made in a RMC plant indicated stable fresh and strength properties for a few months. Furthermore, the production of UFC with onboard mixers was tested. The result confirmed that the method reduced the material-loss during transportation. The surface-finish of UFC was also evaluated by comparing the results obtained from a soil hardness tester. Moreover, the heat curing conditions of UFC were investigated. The result confirmed that the highest temperature and the curing time for the heat curing were lower and shorter than the standard heat curing (at 90℃ for 48 hours), respectively. Chapter 7 "Conclusions" presents the remarkable conclusions in this study and further research for the practical application of the UFC.

Fiber-reinforced polymer (FRP) rods fabricated from unidirectional fibers and a polymer matrix strengthen effectively reinforced concrete (RC) members. The pultrusion is a production method of FRP rod. The FRP rods show various advantages, such as light and no-corrosion. Most FRP rods have higher tensile strength than standard steel bars. Therefore, the FRP rods can be used as an alternative reinforcement of steel bars in RC structures. In addition, FRP rods can be applied in near-surface mounted (NSM) systems for strengthening existing concrete structures. The tensile properties of FRP rods in adhesively bonded anchorages are expected to be studied in detail. Numerous experimental studies were conducted on FRP rods made of glass, carbon, aramid, or basalt fibers. The previous studies have reported that the tensile properties of FRP rods are affected by the shear-lag effect. However, these studies referred to the tensile failure, the shear-lag effect of FRP rods as a phenomenon without a mechanical explanation. Moreover, the effects of mechanical properties of fibers, matrix, fiber-matrix interface on FRP rod properties have not been investigated in detail. To quantify factors affecting the tensile properties of FRP rods, this study performed a numerical investigation on aramid FRP rods to assess the shear-lag effect, tensile load-capacity, and tensile strength. In addition, the effects of fiber, matrix, and fiber-matrix interface on the behavior of FRP material in three dimensions were demonstrated by micro-models. Firstly, two representative volume element (RVE) models of fibers and matrix were proposed to predict engineering constants and strengths of the FRP material in three dimensions. Based on the predicted strength, the criteria were designed. Then, the main simulation, including the FRP rod, the filling material, and the steel tube, was carried out to analyze FRP rods under the variation of interfacial conditions between materials, including full-bonding strength and partiallybonding strength models. In the partially-bonding strength model, the interfaces between materials were simulated as cohesive zone models with the variation of bond strengths and fracture energy release rate. A technique called submodeling was applied to enhance the simulation results. The submodel was cut from the main simulation model and only applied to simulate FRP rods with finer meshes. The study proposed a procedure for calculating the stress distribution in any cross-section of an FRP rod. The simulation results agreed well with the previous experimental study. The findings clearly indicated the position of the failure section in which the tensile stress distribution is unequal. The load-capacity, failure modes, shear-lag effect were predicted based on the maximum stress criterion. The results revealed that the FRP material strengths enforce the failure in two modes associated with the transverse and longitudinal directions of FRP rods. In addition, diameter is a significant factor that increases the shear-lag effect and reduces the tensile strength of the FRP rods. The numerical simulation provided a new method to predict the load-capacity of FRP rods. The study consists of 6 chapters. Outline of the chapter was presented as follows: Chapter 1 introduces about kinds of FRP rods and their application in civil engineering. The chapter shows the research objects, the gaps in composite studies, and the scopes of the present research. Chapter 2 summrizes the review of previous studies related to the theoretical studies of the composite materials. The chapter reveales the gap of theory. In addition, the study compares the advantages and disadvantages of previous studies and proposes methods and models for the present study. Chapter 3 presents the simulations of the representative volume element (RVE) models to determine the mechanical properties and strengths of composite materials. The study investigates the effects of the fiber properties and fiber-matrix interface on composite mechanical properties in detail. The RVE-1 model was employed to predict engineering constants of the FRP material. The RVE-2 was applied to predict the tensile and shear strengths in three dimensions. Chapter 4 shows the numerical simulations of the FRP rod tensile tests with various cases of the materials in Chapter 3. The models are built in two cases of the interface between the FRP rod and filling material: full-bonding and partially-bonding strengths. In the case of the full-bonding strength, three models are built with three hypotheses of FRP rod material. Three models, A, B, and C, were proposed to demonstrate the effect of fiber properties on FRP properties. Model A was built based on the hypothesis that the FRP rod is made of transversely isotropic fibers. Model B was made to simulate with an FRP rod of isotropic fibers. Model C assumes the FRP rod as an isotropic material. In the case of the partially-bonding strength, the study models various interface cases between the FRP rod and the filling materials to investigate the bonding effects. The proposed models were applied to simulate FRP rods from D3 to D8 to analyze the diameter effect. In Chapter 5, the difference between the proposed models was discussed to show the advantages and disadvantages of each model. Firstly, the study compared models (A, B, and C) to highlight the effect of fiber properties on FRP rods. Secondly, the study compared the partially-bonding strength and full-bonding strength models to investigate the bonding effects on the tensile properties of FRP rods. Moreover, the chapter illustrates the existence of the shear-lag effect and demonstrates the diameter effect on tensile strength in FRP rods. Chapter 6 summarizes the novel findings and research significance of the study. In addition, recommendations for future works were also presented.

With the deterioration of bridges as social infrastructure, appropriate maintenance and life extension are required. However, aging degradation of individual bridges is not the same. Since traffic volume and bridge environment are different for each bridge, the degree of deterioration of the bridge is also different. Therefore, it is necessary to identify and eliminate the cause of individual deterioration and to take appropriate measures. This paper focuses on weathering steel bridge that the formation of dense rust is greatly influenced by the environment. The purpose of this study is to clarify the effect of anticorrosion by the environmental improvement which covers the whole steel girder with the metal sandwich panel for weathering steel bridge. Since the space in the girder covered with the metal sandwich panel cannot be expected to have the effect of washing by rainwater or drying and wetting by the flow of wind, the adoption of the metal sandwich panel for weatherproof steel bridge has not been judged until now. In this thesis, the corrosion behavior of weathering steel and the effectiveness of corrosion protection are shown by exposure test, and the corrosion protection effect of environmental improvement by metal sandwich panel is clarified. In addition, this study examines the economical advantages by the metal sandwich panel installation by calculating the life cycle cost. This paper consists of six chapters. Chapter 1 describes the background and purpose of this research. Chapter 2 summarizes previous studies on corrosion protection methods used in steel bridges. In Chapter 3, exposure tests were conducted inside and outside the metal sandwich panel and the following finding were obtained. 1) In the girder covered with the metal sandwich panel, fluctuation range of temperature and humidity is small throughout the year, and it does not follow the sudden weather change of outside of the panel. Since the difference between the temperature and dew point in the panel is large, the wet time in the panel is suppressed to 1/5 or less of the wet time of outside the panel. 2) At the structure which has thin floor slab and low height girder, the temperature rise in the panel may be unavoidable depending on season. However, since the humidity in the panel is low and the wet time is also greatly reduced, the anticorrosive effect can be expected in the steel bridge including the weathering steel bridge. 3) Amount of air born salt into the panel after the metal sandwich panel installation was not detected. In Chapter 4, a small test specimen was placed in the inside space of the steel girder, and the transition of corrosion, anticorrosion effect by environmental improvement and inner surface painting were examined. 1) The untreated steel and the uncoated steel in the ingrown rust region evaluated by the ion permeation resistance method are kept almost same condition after five years. 2) It is also conceivable that the initial salinity of the steel material subjected to the substrate adjustment by blasting exists even after the substrate adjustment, and that the adhering salinity penetrates into the inside of the steel plate at the time of rust formation. However, the increase rate of rust thickness due to aging is slow, and a method of installing a metal sandwich panel after blasting is also effective. 3) Although the effect of environmental isolation from outside the girder was confirmed, it became clear that it was difficult to completely suppress the progress of rust. Chapter 5 examined the economic effects of installing metal sandwich panels on new girders from the beginning and installing them on overbridges 50 years after the star of service. 1) If repainting is required even 1 time during the during the design service period of 100 years, the anticorrosion method by environmental improvement of the metal sandwich panel is economically superior. 2) Accumulating the cost of close visual inspection (for 50 years) of the overbridge that has been in service for 50 years increases the maintenance cost. Chapter 6 summarizes this research and describes future issues.

The reduction of excessive discharge of phosphate into water bodies is a dominant theme to combat the critical eutrophication issue and requires the development of high-performance materials for effective phosphate treatment. In this study, rice straw was used as a raw material for the synthesis of biochar functionalized with layered double hydroxides (BC-LDHs) as efficacious phosphate adsorbents, and their successful synthesis was corroborated via characterization analysis. Experimental investigations, including pH, coexisting anion, reaction time, and initial phosphate concentration effects were systematically performed with selected BC-LDHs 6 and pure LDHs. An optimum pH of 3.0 was observed in both samples. Kinetic and isotherm studies indicated that phosphate adsorption on these samples was controlled by the pseudo-second-order model and the Freundlich model. Comparative kinetic tests also demonstrated that BC-LDHs 6 and pure LDHs reached the equilibrium within 24 h and 3 h, respectively. Nonetheless, the maximum adsorption capacity of the composite was 192 mg/g, which was higher than that of pure LDHs (166 mg/g). The coexistence of various anions negligibly affected the removal efficiency of the composite; however, fluoride was the most competitive anion for adsorption on pure LDHs. The adsorption mechanisms of the composite involved electrostatic interaction, inner-sphere complexation, pore diffusion, precipitation, and reconstruction. Furthermore, phosphate adsorbed on both materials could be easily recovered by 0.1 M NaOH solution owing to the displacement reaction between phosphate and hydroxyl ions. Additional evidence from reusability experiments exhibited that the composite could maintain its good adsorption performance even after three adsorption-desorption cycles. The transformation of BC-LDHs 6 after its usage in phosphate treatment (P-BC-LDHs 6) into a fertilizer was further explored by using seed germination and early growth assays of lettuce through a comparison with phosphate-loaded LDHs (P-LDHs). Lettuce seeds germinated in all P-BC-LDH 6 treatments showed undesirable growth characteristics compared with the controls, while total germination failure was observed under high concentrations of P-LDHs. In the latter experiments, the optimal application rates for plant growth were 2.5% for P-BC-LDHs 6 and 1.0% for P-LDHs. The considerably greater biomass development and length of lettuce were visible in samples delivered from P-BC-LDHs 6 compared to those from P-LDHs. The results obtained suggest that BC-LDHs 6 is a promising adsorbent for phosphate treatment and post-adsorption BC-LDHs 6 has the application potential to serve as a fertilizer for horticultural crop production.